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Thread: Really Dumb Planer Question, Probably

  1. #1

    Question Really Dumb Planer Question, Probably

    I just bought an older (1994, I believe) Powermatic Model 15 planer. This is the first planer I've owned. The seller demoed it for me before I bought it. It works, but needs some basic TLC (cleaning, tune up and knives).

    I took the covers off and was exploring the machine earlier today and noticed something strange (to me, at least). When I moved the belts by hand to look at the knives, the roller drive chains on the other side didn't appear to move. I haven't touched the gear selector other than to make sure it was pushed in. I'm not able to run the machine in my shop yet because I haven't had time to get the right plug, so I haven't been able to turn it on to check it.

    Is this normal? Things going through my head:

    - The machine got bumped into neutral on the ride home, and even though I pushed the gear selector in (it didn't move), it's still in neutral because things need to be turning for it to go back into gear
    - The gearing is so low between the cutterhead and the feed rollers that it probably was moving and just didn't look like it because I was turning the cutterhead so slowly by hand
    - The gearbox is some kind of spring or pressure driven unit (like a centrifugal clutch) that needs high cutterhead speed in order to engage
    - It's broken
    - I'm an idiot

    Anyone know how these gearbox internals are set up? Picture in the manual wasn't much help, although I didn't see any springs or clutches, so I'm thinking it's direct drive off the cutterhead.

    Thanks in advance!

  2. #2
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    I may not be visualizing this right but, the motor probably turns about 3450 RPM. This means the pulley makes a rotation nearly 60 times per second. The point being that the difference in speed between the belts versus the feed rollers via the transmission is quite large. If you turn the belts by hand about 50 rotations you will probably see the feed roller chain move a bit .
    Take me to the hotel - Baggage gone, oh well . . .

  3. #3
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    Is it two speed on the feedrate? If so there is a neutral between the two and an off position as well. Put a mark on the chain(clothes pin) and spin the head 50-60 times and see if it moves at all.
    Bill D.

    Edit: Delta lunch box is 12-14fpm. For a two inch feedroll that is 24 or 28 rpm.
    3600/24=141
    So 141 turns of the cutter head will spin the feed roller one time.
    Last edited by Bill Dufour; 01-17-2022 at 12:51 AM.

  4. #4
    The rollers do turn at a much, much slower rate than the head - think several thousand rpm’s vs maybe 20?

    If it wasn’t turning, the planer wouldn’t have worked properly.

  5. #5
    Join Date
    Dec 2019
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    Columbus, OH
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    Planers usually cut in the range of 100-300 cuts per inch (really ballparking that range). The gearing will depend on feed roller size, but assuming a 1.5" diameter feed roller and a 3 knife cutter, 200 cuts per inch means the roller spins once when the knives spin 300 times.

    When I change the knives on my lunchbox planer, I never see the rollers spin, and when I need to clean the rollers I always power cycle it to rotate them and clean from below (with the machine unplugged)

  6. #6
    The feed rollers should move aprox .0426 inch per revolution of the cutterhead at the slower 16FPM feed rate. 4,500 RPM, 13,500 cuts per minute, 16 feet per minute. Here's a link to the manual and specs. https://content.powermatic.com/asset...210_man_EN.pdf

  7. #7
    Thanks for all the responses. Got the correct plug and wired it up today. Works fine.

    So, as it relates to my list of possibilities above, #2 and #5 are confirmed! ;-)

    If I remember, I'll put my photo-tachometer on the cutterhead and feed rollers to calculate the actual reduction, but it's something like 150:1 at low speed and 118:1 at high speed, assuming 2" feed rollers. With 1.5" feed rollers, it would be 110:1 at low speed and 88:1 at high speed.

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